1. Field of the Invention
This invention relates to an endless stainproof woven fabric which is woven from monofilaments of synthetic resins and is used for paper making. More particularly, it relates to such a woven fabric which is suitable for use as a wire in making paper, e.g. kraft paper, corrugating medium paper, liner boards or paperboards from waste paper containing gum pitches by reclamation thereof. The invention also relates to a method for making such a woven fabric as mentioned above.
2. Description of the Prior Art
Unlike metallic wires, synthetic resin-made woven fabrics for paper making, when used as wires, are disadvantageously apt to stain due to the deposition thereon of tacky particles called gum pitch, which is a kind of resin contained in starting waste paper. To avoid this, a variety of methods have been proposed and have actually been in use. In one such method, a resin film made of a mixture of a fluorine resin powder with a thermosetting resin is formed on the surfaces of yarns of a woven fabric. Another method is described in U.S. Pat. No. 3,573,089 in which a hydrophilic resin film is formed similarly to the previous method. The former method in which a resin film containing a fluorine resin powder is formed on the yarns is an attempt to make use of the non-tackiness of the fluorine resin. Since the fluorine resin itself cannot adhere directly to the surfaces of the yarns of the woven fabric, a resin used as a binder is essential. In this case, the fluorine resin powder is buried in the binder resin whereby it is difficult for the former to be exposed to the surface of the resin film, so that the stainproof effect caused by the non-tackiness inherent to the fluorine resin is not fully exhibited.
In the latter method in which a hydrophilic resin film is formed on the surfaces of the yarns of a woven fabric, the resin film so formed is poor in water resistance, resulting in the loss of the stainproof effect within a short time due to the elution of the hydrophilic material although the effect is appreciated initially.
As will be apparent from the above, the known stainproof methods have never provided stainproof fabrics which can maintain their stainproof effect throughout their service life. In paper-making industries, stained woven fabrics have to be frequently washed forcibly by the use of chemicals or highly pressurized shower. This places on the part of the makers substantial burdens including the damage of the woven fabrics and the loss time caused by suspending the operation of paper-making machines.